Transmission problem

I backed out of the garage yesterday morning just fine. shifted to drive and the engine just revved - no movement. reverse works, forward gears don’t. My brother-in-law (he listens to cartalk, too) suggested backing up all the way to work. Question: what do I do with that bum? Really, any ideas on the transmission? I have a parts car but am hoping for and easy fix so i don’t have to swap transmissions. The car is actually an '83 300D Turbo but the 240D below was the closest choice and i think the same tranny. Thanks. My last resort is to call Tommy and Ray.